The present invention relates to an illumination device, and more particularly to a backlight used in a liquid crystal display device.
A TFT (Thin Film Transistor) type liquid crystal display device has been popularly used as a display device of a liquid crystal television receiver set, a personal computer or the like. The liquid crystal display device is constituted of a liquid crystal panel having a drain driver and a gate driver arranged on a periphery thereof and a back light radiating light to the liquid crystal panel.
The backlight is classified into an edge-light-type backlight and a direct-type backlight. One of crucial tasks that both backlights possess is the acquisition of a uniform backlight by suppressing brightness irregularities.
As one of means for suppressing brightness irregularities, there has been proposed a technique which can reduce the brightness irregularities by forming a reflector mounted on a bottom surface of the backlight in an optically suitable shape different from a simple planar shape. Patent document 1 (JP-A-2003-31003) and Patent document 2 (JP-A-2006-260924) disclose such a technique.
An illumination device used in the backlight of the liquid crystal display device includes a reflector on a side thereof opposite to a light radiating surface (a bottom surface of the backlight). To enhance the uniformity of the light radiating surface of the backlight, it is preferable to form, not a usual planar shape but a surface having a bent shape such as a wave shape. As a simple method for forming the shape of the reflector into such a shape, it may be possible to mount a mold made of iron or resin and having such a shape on a bottom surface of the backlight and, then, to adhere a reflection sheet reflecting light to the mold. However, due to the adhesion of an extra material to the reflection sheet, there arises a drawback that the backlight becomes heavy.
It is an object of the present invention to provide, in a liquid crystal display device which includes a backlight, the simple structure of a backlight having a reflector of an arbitrary shape.
The above-mentioned and other objects and novel features of the present invention will become apparent from the description of this specification and attached drawings.
The present invention has been made to overcome the above-mentioned drawbacks. To briefly explain the summary of typical inventions among the inventions described in this specification, they are as follows.
(1) According to a first aspect of the present invention, there is provided a liquid crystal display device which includes: a liquid crystal panel; and a backlight arranged on a side opposite to a display screen of the liquid crystal panel, wherein the backlight includes a light source and a reflector for reflecting light radiated from the light source toward the liquid crystal panel, and the reflector has a shape thereof determined due to the fixing of the end portions of the reflector to the backlight.
(2) According to a second aspect of the present invention, there is provided a liquid crystal display device which includes: a liquid crystal panel; and a backlight arranged on a side opposite to a display screen of the liquid crystal panel, wherein the backlight includes a light source and a reflector for reflecting light radiated from the light source toward the liquid crystal panel, and the reflector forms a bottom surface of the backlight.
(3) According to a third aspect of the present invention, there is provided a liquid crystal display device which includes: a liquid crystal panel; and a backlight arranged on a side opposite to a display screen of the liquid crystal panel, wherein the backlight includes a light source and a reflector for reflecting light radiated from the light source toward the liquid crystal panel, the reflector has a shape thereof determined due to the fixing of the end portions of the reflector to the backlight, and the reflector forms a bottom surface of the backlight.
The present invention provides an illumination device having a simplified structure which can simply form a shape of a reflector and, at the same time, can acquire both the uniformity of brightness of the illumination device and the reduction of thickness of the illumination device.
To be more specific, according to the present invention, a back lid of a lower frame which houses a backlight device therein can be eliminated and hence, a weight of the backlight can be largely reduced. Particularly, the lower frame is often made of a metal and hence, the elimination of the back lid brings about a large weight reduction effect. Further, the elimination of the back lid also brings about the reduction of a part cost and an assembly cost.
Further, according to the present invention, even when an edge-light-type backlight is used, light from a light source can be directed toward a liquid crystal panel without using a so-called light guide plate thus realizing the reduction of weight and the reduction of cost of the backlight.